Commercially available solar collectors typically convert solar radiation incident on a generally wide area to electrical or thermal energy which is subsequently transported in the converted form to a point of use. Because of some of the inherent practical and technical limitations of large area solar conversion devices, attempts have been made to concentrate the solar radiation impinging over a wider area and focusing it onto a smaller area conversion device. Among the typical solar energy concentrators employed are mirrors, lenses and fluorescent devices.
In U.S. Pat. No. 668,404, use of a mirror for focusing solar radiation onto a point of use is disclosed. A more recent solar concentrator based on the use of reflecting solar radiation with mirrors and focusing it at a collection point is disclosed in U.S. Pat. No. 4,130,109. Since the relative position of the sun and earth changes with time, there are certain practical limitations with respect to using mirrored surfaces for focusing solar radiation at a point of use.
In U.S. Pat. No. 4,148,300 and U.S. Pat. No. 4,114,592, lens type devices are disclosed for focusing solar radiation on a point of use. As undoubtedly will be appreciated, high quality lenses for such applications are expensive and consequently are not suitable to extremely widespread use.
In U.S. Pat. No. 4,175,980 and U.S. Pat. No. 4,149,902, there are described different types of fluorescent concentrators in which solar radiation is collected over large flat areas and focused onto a smaller area for the photovoltaic conversion of the focused radiant energy by means of a photovoltaic device. Indeed, in U.S. Pat. No. 4,149,902, the photovoltaic device is contiguous with the fluorescent collector. In one embodiment of U.S. Pat. No. 4,175,980, however, the photovoltaic device is not contiguous with the fluorescent concentrator but is separated from the concentrator by means of a fiber optic mechanism. In the former patent, however, the amount of light utilized is limited by the cross-sectional area of the solar cell and, in the latter patent, the amount of light utilized is limited by the cross-sectional area of the fiber optic mechanism.